Effects Of Tillage Practices On Greenhouse Gases Emissions From A Purple Soil Under Rice-rape Rotation System

Climate warming is a global environment issue today, the main reason for this issue is the increasing concentration of greenhouse gases in atmosphere, andCH4、CO2and N2O has been paid much attention due to their substantial contribution to global warming. They in atmosphere have a double bad effect and this impact has become increasingly evident through a variety of ways.The main sources of CO2are fossil fuel use and land-use change, while the main source of N2O is agricultural activity. It is easily find that agricultural production activity has enormous effect on the concentration of greenhouse gases in atmosphere. Tillage is an important part of agricultural activity, and there is a significant difference of the emission of greenhouse gases from farm ecosystem under different tillages.Based on the observation of CH4CO2and N2O emission from soil-crop ecosystems, seasonal variation characteristic, influences factors and CH4CO2and N2O emission trends in each growing season were discussed in this paper. CH4CO2and N2O emission were measured by static chamber-gas chromatographic techniques. The tillage experiment was established in the Key Field Station for Monitoring of Eco-Environment of Purple Soil of the Ministry of Agriculture of China, located in the farm of Southwest University (30°26’N,106°26’E), Chongqing. Four tillage treatments including conventional tillage with rice only system (DP), conventional tillage with rotation of rice and rape system (SH), no-till and plain culture with rotation of rice and rape system (XM), no-till and ridge culture with rotation of rice and rape system (LM)were selected as research objectives. Results were as following:1. The changes of CH4emission flux under different tillage systemsIn rape season, CH4emission fluxes under different tillage systems had similar trends in2009-2010and2010-2011. All treatment had low CH4emission fluxes and there were no significant differences between different tillage systems. Most CH4emissions were in the rice growing season in the whole year. Therefore, taking control of CH4emissions in rice growing season could reduce farmland CH4emissions.In rice season, CH4emission fluxes under different tillage systems had similar trends in 2009-2010and2010-2011, each treatment and inter-annual trend all showed a bimodal shape. One-way ANOVA showed that the DP CH4emission flux during the rice season was significantly greater than LM, XM and SH treatment (p<0.05) in2009-2010and2010-2011. The results showed that SH treatment can significantly reduce the emission of CH4in rice season. The CH4emission characteristics and results in fallow period were similar to the rice season.In2009-2010and2010-2011, the annual CH4emissions ranked of DP>LM>XM>SH. Analysis of variance showed DP treatment annual CH4emissions significantly higher than LM, XM and SH treatment (p<0.05), indicating that compared with conventional tillage, no-tillage and crop rotation could reduce CH4emissions, and the reduction effect of SH treatment was most obvious.Affect farmland CH4emission factors, temperature played a very important role of CH4production and emission process. On LM, the XM and SH processing in2009-2010and2010-2011rapeseed season and fallow periods CH4emission flux with three temperature correlation analysis shows that three temperatures rice season CH4fluxes were significantly relationship (p<0.05), which the underground at5cm temperature with rice quarter CH4emission flux of the highest correlation. In the farming methods of the rape growing season and fallow periods between CH4emission flux and WFPS was no significant correlation. Show that these types of factors are not independent influence CH4emissions, but the combined effect of farmland CH4emissions.2. Farmland ecosystem respiration rate change under different tillageIn2009-2010and2010-2011Rape quarter, the other three farming methods ecosystem respiration rate were higher than the DP processing, DP processing throughout the growing season ecosystem respiration rates are lower and smaller changes.2009-2010the total ecosystem respiration rate is generally higher than the2010-2011total ecosystem respiration rate, but in general,2009-2010and2010-2011CO2ecosystem respiration rate changes over time,but the trend was basically the same, showed for the first and then decreased.In the rice growing season2009-2010and2010-2011the four processing of the total ecosystem respiration consistent trend over time, the different tillage ecosystem respiration were XM> LM> SH> DP.Temperature is the main factors that affect farmland ecosystem total respiratory the surface temperature processing of two no-tillage farmland ecosystem breathing significant underground5cm temperature treatment of SH greatest impact. However, of WFPS and depth of respiration rate under various farming methods was not significant.3. N2O flux change in farmland under different tillageRape growing season, the DP processing N2O emissions is relatively stable, and emissions are always floating in zero up and down, while the other three treatments, N2O emissions has a significant volatility, and there is a clear emissions in different planting period.2009-2010and2010-2011rapeseed growing season N2O flux,2009-2010is basically the same trend over time of four farming methods average N2O flux were SH> LM> XM> DP,2010-2011SH> XM> LM> DP. Plant or oilseed rape does not change the status of N2O emissions, no-tillage compared to traditional crop rotation, can effectively reduce soil N2O emissions.N2O flux in the respective processing of different periods of the rice season in2009-2010and2010-2011, although there were differences, but basically had same trend over time. Each treatment in2009-2010the average N2O flux LM> DP> SH> XM; processing in the years2010-2011the average N2O flux ranked of LM> SH> DP> XM, and LM treatment N2O emission fluxes significantly higher than XM, showed that during the rice cultivation, N2O emissions of XM treatment significantly inhibited.SH5cm underground temperature of N2O emissions in2009-2010significantly, three temperatures farmland N2O emissions were not significantly affected. The relationships between WFPS and LM N2O emission were significant in2009-2010and2010-2011, and there were no significant impact on other treatments of N2O flux.